No Stupid Questions

In a comment you mentioned you're the team lead. Maybe you already are, but just in case: stop thinking about it in terms of the individual personal relationship and start thinking about it in terms of the team dynamic. It's unlikely this only affects you, so even if their individual work performance is fine, does their behavior affect other people's performance or happiness at work? If it's affecting others negatively it's your responsibility to protect them and their work output, even if that means finding a new team for this person or documenting a path to letting them go altogether.

I don't envy you. Good luck.

(Disclaimer: armchair expert here, admittedly with some personal experience)

Poor guy. Rejection sensitivity is a thing, and it sounds like this guy's got it bad. Some people essentially walk around with the emotional equivalent of a bad sunburn - even a casual touch can be pretty nasty.

If he's as socially awkward as this suggests, the whole "setting boundaries" thing is likely hard for him to deal with, and his reaction suggests that he's never learned to handle feedback very well. I'm assuming there's no hint of malice, just childishness and being oblivious of social norms. 46 years' worth of subtle or overt feedback along the lines of "you're not pulling this social thing off" can make people do some weird and counterproductive things in order to try to fit in. It can also sensitize them extremely to criticism no matter how accurate, necessary and well-intentioned.

If you can make sure he knows you're on his side, and are very careful to not make things sound like an attack, you have a reasonable chance of getting through. He is distinct from his fart jokes, and people don't dislike him but specific bits of inappropriate behavior. Since any hint of rejection tilts him, help him be secure in the ways he's valued. If he's got the classic "bad with subtext" thing then you need to be prepared to spell things out, while keeping it inoffensive. As a hunch, I'd stay well away from anything that sounds like a judgment either on your part or anyone else's - stick to the facts. This is what happens when people get distracted, humor is important in the workplace but there's a time and place, etc.

That being said, you don't need to coddle him too much (particularly if he's either guilty about needing it, or suspects it's not genuine) but it's ideal if it works - he's happier and stops setting himself up for "rejection", everyone else is happy due to less friction in general, you're happy, your boss is happy.

If that doesn't work, it might be time for brass tacks: "this specifically doesn't work, it doesn't mean people hate you, but it does need to stop." In the extreme, he could dig in and then you might want to call backup from e.g. your superior or someone less hands-on.

Have you tried... you know... talking to him about it?

I mean a cool headed calm discussion avoid not making farther noises.

I guess it depends on the culture of your work place but honestly I feel like this is something that can be easily resolved and it's part of managing a team.

I'd just be straight with him, in a kind manner tell him his behavior is something you're having a hard time with, that you expect him to take your feedback on board, and that you're not interested in dealing with him acting out because his feelings got hurt.

Document everything, give him a chance to modify his behavior and if he persists, you've given him a chance and now it's time to talk to HR because you've done everything you can reasonably be expected to do. It's not your fight anymore.